If you had mentioned the south Oregon coast (or Calif Redwoods) first, you would have gotten different answers.
The two most recommended routes to that part of the coast are CA20, and US199. CA299 from Redding has been discussed recently, the main opinion being that it is long with lots of curves and ups/downs, though not difficult.
For CA20, take I80 west of Reno. 20 past Clear Lake is the easiest way to US101.
For US199, take the Reno, Susanville, Mt Shasta route, and I5 to Grants Pass. US199 has some curves along the river on the California side, but nothing difficult. An alternative in Oregon is to continue north of Roseburg, and take OR42 to the coast.